1. Field of the Invention
The present invention relates to a process for preparing aqueous extracts of plants and to the aqueous extracts thus obtained, some of which find application in medicine, particularly in the treatment of immune suppressant diseases or in the treatment of viral diseases.
2. Description of the Related Art
Plants and, in general, vegetals, remain an important source of active compositions and compounds employed in medicine. New plants, new compounds present in plants or even modifications of compounds present in plants are of potential interest to the phitochemical industry.
The methods employed in the extraction of the components of vegetals and plants are of great importance regarding not only the yields of the compounds to be obtained, but also the chemical nature of the compounds which can in fact be gained.
The usual methods employed in the phitochemical industry are based on the extraction of the comminuted plant or vegetal with water or steam, with organic solvents, or with mixtures of water and organic solvents such as water and alcohols. The inclusion of a maceration step is also well known in the art. Finally, the separation of the aqueous extract from the solid phase can be effected by conventional methods such as decantation, centrifugation or filtration. Additional chemical treatments to modify the structure of the compounds present in the plants can also be effected. See Dr. Pio Font Quer, “Medicinal Plants. The updated Discorides” Ed. Labor, S.A., 12th Edition, 1990.
The French patent FR 2733419 (“the '419 patent”) describes the preparation of extracts of a mixture of at least three different plants selected from the genus Geranium, Plantago and Calendula by steeping 300-400 g of fresh Geranium robertanium leaves, 10-50 g of dried Plantago lanceolata leaves and 10-50 g dried Calendula officinalis leaves in 3 l. of water at 15-30° C. for 3-15 days. According to the '419 patent, the composition thus obtained can be used in the treatment of cancer. However, these extracts produce non-satisfactory activity, as reflected in the examples below.
The European patent application EP 0 934 746 A (“the '746 application”) discloses the preparation of an aqueous extract of plants from the genus Geranium and Plantago as well as from the species Calendula officinalis, in which these extracts are obtained from the following amounts in grams of these plants in water: 10 to 60 of dried Geranium sibiricun or 300 to 360 of fresh Geranium sibiricum, 10 to 60 of dried Plantago lanceolata, and 10 to 60 of dried Calendula Officinalis in 300 grams of water. The method for producing these aqueous extracts comprises macerating the comminuted plants in water before press-filtering the mixture and submitting it to a centrifugal treatment. According to the '746 application, this extract may be used in oncological practice as part of a cancer therapeutic program. However, these extracts produce non-satisfactory activity as reflected in the examples below.
There is, thus, a need for methods of preparing alternative extracts of plants which can be used as therapeutic agents, and which eventually can provide access to new compounds.